1. Field of the Invention
The present invention relates to a floating presser foot for a quilting machine and, more particularly, to a presser foot suspension and drive system which substantially eliminates the noise, vibration, and wear normally associated with quilting machine presser foot systems.
2. Description of the Prior Art
Quilting machines of the general type including a bed plate, material supporting means including material feeding means for conducting material to be quilted over the bed plate, sewing thread supply means, a plurality of vertically reciprocal needles mounted on a needle support bar positioned above the bed plate for moving a plurality of threads through the material and the bed plate, vertically reciprocal presser foot means positioned above the bed plate for holding the material on the bed plate during formation of the stitches and for holding the material during removal of the needles therefrom, thread take-up means positioned between the thread supply means and the needles for controlling the tension in the threads during the formation of the stitches, and pattern controlling means for moving the material supporting means laterally in a preselected relationship with the material feeding means for obtaining sewing patterns, are generally old and well known in the art. An early quilting machine of this type is shown in U.S. Pat. No. 260,994, issued July 11, 1882, to William Koch. Since that time, such machines have become substantially more complex and a quilting machine of the type generally available today is shown in U.S. Pat. No. 3,385,246, issued May 28, 1968, to Kurt Schlegel. For a discussion of a modern, high speed quilting machine, reference should be had to my copending U.S. patent application Ser. No. 648,002, filed concurrently herewith.
Such machines stitch together an assembly of quilting fabrics and a filler in a pattern of stitches distributed throughout the area of the assembly. In the quilting operation, the fabrics are drawn from supply rolls while the filler is drawn from a supply roll between the fabrics to form an assembly of filler sandwiched between an upper and lower fabric. The assembly is then passed through the stitching mechanism by means of drawing rollers.
The stitching mechanism is a stationary unit and the bed place has a plurality of holes therein, spaced transversely of the direction of movement of the material assembly, through which the needles may pass downwardly to shuttles or bobbins mounted beneath the bed plate, one for each hole and needle. Stitches are made by a downward movement of the needles through the material assembly and into and through the holes in the bed plate. Upon upward movement of the needles, loops are formed in the threads, below the bed plate, through which the shuttles or bobbins conduct second lengths of thread, whereupon the needles are further withdrawn and the threads pulled tight to form the stitches.
During the stitching operation, the presser foot is first lowered onto the material assembly to hold it in place on the bed plate and then elevated slightly to permit forward movement of the material assembly. The presser foot also limits upward movement of the assembly so that the needles may be withdrawn therefrom. The presser foot includes a similar plurality of transversely oriented holes, aligned with the holes in the bed plate, for passage therethrough of the needles during the stitching operation.
In a conventional quilting machine, the presser foot is supported at a plurality of spaced locations by brackets which are connected to the lower ends of vertically oriented rods which extend through a plurality of spaced, rigid bearings. Thus, the bearings support the rods, the brackets, and the presser foot for vertical reciprocation relative to the bed plate. A spring is typically positioned around each support rod, between its associated bearing and bracket, to normally urge the presser foot downwardly into contact with the bed plate or the material thereon.
The presser foot is normally driven by the same oscillatory shaft which is utilized to vertically reciprocate the needles of the quilting machine. That is, by mounting a plurality of spaced eccentrics on the needle drive oscillatory shaft and an eccentric follower on each presser foot support rod, the eccentrics may be utilized to cyclically lift the presser foot off the bed plate, compressing the springs. In another position of the oscillatory shaft, the eccentrics release the eccentric followers and the springs are permitted to force the presser foot downwardly onto the bed plate.
In a conventional quilting machine, of the type described above, the springs surrounding the presser foot support rods literally thrust the presser foot downwardly onto the bed plate when the eccentrics release the eccentric followers. This action has proven to be one of the greatest sources of noise, vibration, and wear associated with conventional quilting machines. The noise creates an unpleasant working environment for the machine operators. The vibration contributes to the problem of thread breakage, thereby limiting the productivity of the quilting machine. The vibration also causes excessive wear of the parts so that the machine must be overhauled relatively frequently. Furthermore, because of the thread breakage and other problems, the machine must be constantly monitored by a relatively highly skilled operator, thereby increasing operating costs.